URL Rewrite

URL Rewrite技术

 
URL Rewrite技术。该技术的核心方程是在服务器端，主要通过服务器的重写技术，一种基于正则表达式的重定向技术。

原理如：index.php?id=124这个地址，服务器事先定义，/可以替换，重写为?id=则，这个地址就变成index.php/124。这个定义的意思是说，当服务器www.twomaxinter.com接受到一个http请求，请求访问其上的index.php/124这个文件时，先通过Rewrite对该地址进行重写，然后载入重写后的地址，进行解析。这样当你访问http://www.twomaxinter.com/index.php/124时，并没有直接到达这个文件，而是这个地址，在服务器那里被换掉了，而这个换掉的过程，对客户端而言是隐蔽的，不可知的。

这里说的，只是原理，简单的替换，事实上，URL Rewrite还可以做许多更复杂的代换。如喜悦国际村的，由showthreads.php?postid=12345转换为12345.html。具体可以参照apache手册中的说明。

为什么要应用URL Rewrite技术。

从原理上可知，这种技术并不能实际提高访问速度，减少负载，与生成静态页面有着本质上的区别，但为什么有那么多网站热衷于此呢？说到这里，我们不得不提到搜索引擎。搜索引擎后台的蜘蛛引擎可以动态抓取互联网上的页面，经分析后存入数据库。但动态页面，一般却是不被蜘蛛引擎考虑的，只有很少部分，可能会被自动收录进去。而蜘蛛引擎识别静态页面和动态页面是从一点基本点着手，即静态页面一般不包含参数。即?id=...&post=..之类的。而动态页面多有这个东西。所以蜘蛛引擎在收录过程中，?后的部分基本是不考虑的。这样造成的结果就是showthreads.php?id=123456由于?后部分被忽略，就变成了showthreads.php。当然这个页面并不具备任何实际内容的。即，URL Rewrite技术多为搜索引擎而来。

具体的URL Rewrite方法，参数，可参阅apache手册中URL Rewrite部分。及以下地址：

http://linux.dalouis.com/doc/apache2.0/misc/rewriteguide.html

希望对各位，能够有所帮助。

 

Trackback: http://tb.blog.youkuaiyun.com/TrackBack.aspx?PostId=1191944

给个代码大家参考:

htaccess tips Part 2. How to rewrite advanced url's on apache

Part 1. is here: http://forums.seochat.com/showthread.php?p=121601

I have test all this. Use absolute paths for everything, example:
<img src=""/>

Some quick stuff:
([a-z]+) - just small letters
([A-Z]+) - just big letters
([0-9]+) - just numbers
([a-zA-Z_-]+) - small and big letters and minus (-)
([a-zA-Z0-9_-]+) - small and big letters, numbers and minus (-)

(.*) - everything - warning!!!! don't ever use - this have to much permissions

Example 1.

www.domain.com/index.php?category=search-engine-optimization

1. solution:
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^([a-zA-Z0-9_-]+)$ index.php?category=$1 [R=301,L]

results: www.domain.com/search-engine-optimization

2. solution:
Code: 

Options +FollowSymLinks
RewriteEngine On
RewriteRule ^category/([a-zA-Z0-9_-]+)$ index.php?category=$1 [R=301,L]

 

results: www.domain.com/category/search-engine-optimization

3. solution
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^([a-zA-Z0-9_-]+).html$ index.php?category=$1 [R=301,L]

results: www.domain.com/search-engine-optimization.html

4. solution
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^category/([a-zA-Z0-9_-]+).html$ index.php?category=$1 [R=301,L]

results: www.domain.com/category/search-engine-optimization.html

5. solution
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^category/([a-zA-Z0-9_-]+)/$ index.php?category=$1 [R=301,L]

results: www.domain.com/category/search-engine-optimization/

 

 

Example 2.

www.domain.com/index.php?category=internet&subcategory=search-engine-optimization

 

1. solution:
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^([a-zA-Z0-9_-]+)/([a-zA-Z0-9_-]+)$ index.php?category=$1&subcategory=$2 [R=301,L]

results: www.domain.com/internet/search-engine-optimization

2. solution:
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^category/([a-zA-Z0-9_-]+)/subcategory/([a-zA-Z0-9_-]+)$ index.php?category=$1&subcategory=$2 [R=301,L]

results: www.domain.com/category/internet/subcategory/search-engine-optimization

3. solution:
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^([a-zA-Z0-9_-]+)/([a-zA-Z0-9_-]+).html$ index.php?category=$1&subcategory=$2 [R=301,L]

results: www.domain.com/internet/search-engine-optimization.html

4. solution:
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^category/([a-zA-Z0-9_-]+)/subcategory/([a-zA-Z0-9_-]+).html$ index.php?category=$1&subcategory=$2 [R=301,L]

results: www.domain.com/category/internet/subcategory/search-engine-optimization.html

5. solution:
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^category/([a-zA-Z0-9_-]+)/subcategory/([a-zA-Z0-9_-]+)/$ index.php?category=$1&subcategory=$2 [R=301,L]

results: www.domain.com/category/internet/subcategory/search-engine-optimization/

 

Example 3.

www.domain.com/index.php?category=internet&subcategory=search-engine-optimization&more=articles

 

1. solution:
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^([a-zA-Z0-9_-]+)/([a-zA-Z0-9_-]+)/([a-zA-Z0-9_-]+)$ index.php?category=$1&subcategory=$2&more=$3 [R=301,L]

results: www.domain.com/internet/search-engine-optimization/articles

2. solution:
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^category/([a-zA-Z0-9_-]+)/subcategory/([a-zA-Z0-9_-]+)/more/([a-zA-Z0-9_-]+)$ index.php?category=$1&subcategory=$2&more=$3 [R=301,L]

results: www.domain.com/category/internet/subcategory/search-engine-optimization/more/articles

3. solution:
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^([a-zA-Z0-9_-]+)/([a-zA-Z0-9_-]+)/([a-zA-Z0-9_-]+).html$ index.php?category=$1&subcategory=$2&more=$3 [R=301,L]

results: www.domain.com/internet/search-engine-optimization/articles.html

4. solution:
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^category/([a-zA-Z0-9_-]+)/subcategory/([a-zA-Z0-9_-]+)/more/([a-zA-Z0-9_-]+).html$ index.php?category=$1&subcategory=$2&more=$3 [R=301,L]

results: www.domain.com/category/internet/subcategory/search-engine-optimization/more/articles.html

5. solution:
Code:
Options +FollowSymLinks
RewriteEngine On
RewriteRule ^category/([a-zA-Z0-9_-]+)/subcategory/([a-zA-Z0-9_-]+)/more/([a-zA-Z0-9_-]+)/$ index.php?category=$1&subcategory=$2&more=$3 [R=301,L]

results: www.domain.com/category/internet/subcategory/search-engine-optimization/more/articles/

more resources:
Apache mod rewrite docs
Apache RewriteBase docs
Mod rewrite forum
Absolute and Relative paths
SEW mod rewrite tips and tricks

url rewrite概述

最简单的是基于各种WEB服务器中的URL重写转向（Rewrite）模块的URL转换：
这样几乎可以不修改程序的实现将 news.asp?id=234 这样的链接映射成 news/234.html，从外面看上去和静态链接一样。

当我需要将将news.asp?id=234的映射成news/234.html时，只需设置：
RewriteRule /news/(/d+)/.html /news/.asp/?id=$1 [N,I]
这样就把 /news/234.html 这样的请求映射成了 /news.asp?id=234
当有对/news/234.html的请求时：web服务器会把实际请求转发给/news.asp?id=234

而在IIS也有相应的REWRITE模块：比如ISAPI REWRITE和IIS REWRITE，语法都是基于正则表达式，因此配置几乎和apache的mod_rewrite是相同的：

比对于某一个简单应用可以是：
RewriteRule /news/(/d+)/.html /news/news/.php/?id=$1 [N,I]
这样就把 http://www.52net.com/news/234.html 映射到了 http://www.52net.com/news/news.php?id=234

一个更通用的能够将所有的动态页面进行参数映射的表达式是：
把 http://www.myhost.com/foo.php?a=A&b=B&c=C
表现成 http://www.myhost.com/foo.php/a/A/b/B/c/C 。
RewriteRule (.*?/.php)(/?[^/]*)?/([^/]*)/([^/]*)(.+?)? $1(?2$2&:/?)$3=$4?5$5: [N,I]

通过URL REWRITE还有一些好处：

隐藏后台实现：这在后台应用平台的迁移时非常有用：当从asp迁移到java平台时，对于前台用户来说，根本感受不到后台应用的变化；
简化数据校验：因为像(/d+)这样的参数，可以有效的控制数字的格式甚至位数；
比如我们需要将应用从news.asp?id=234迁移成news.php?query=234时，前台的表现可以一直保持为 news/234.html。从实现应用和前台表现的分离：保持了URL的稳定性，而使用mod_rewrite甚至可以把请求转发到其他后台服务器上。

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